JP4285299B2 - Paper feed roller - Google Patents

Description

  The present invention relates to a paper feed roller, and more specifically, is made of a rubber composition containing short fibers, and improves the orientation direction of the short fibers to suppress fluctuations in the friction coefficient.

  Paper feed rollers made of rubber rolls are used in paper feed mechanisms such as various printers, electrostatic copying machines, plain paper facsimile machines, and automatic deposit payment machines (ATMs). The paper feed roller of the present invention refers to a paper feed roller, a registration roller, a transport roller, and / or a transfer roller that contacts the paper and transports the paper by rotation and friction on the roll surface. The coefficient of friction on the surface of the paper feed roller is affected by deposits on the roll surface. For example, when paper dust adheres to the roll surface, there is a problem that paper conveyance failure occurs.

Thus, Patent Document 1 proposes a paper feed roller from a rubber composition containing glass fiber. A part of the glass fiber is exposed on the surface of the paper feed roller, and the exposed portion of the glass fiber has an effect of scratching the paper surface. Such a scratching effect is not easily disturbed by the adhesion of paper dust, and thus it is possible to reduce paper conveyance failure as described above.
Since the rubber composition containing the short fibers becomes hard, the contact area with the paper surface is reduced, and the friction coefficient of the roll surface tends to be lowered. However, it is sufficient for the paper feed roller to have a coefficient of friction necessary for feeding paper, and no further coefficient of friction is required.

  In recent years, in various printers and the like, with the spread of colorization and the demand for higher image quality, polymerized toner has been used in place of conventional toner manufactured by a pulverization method. The polymerized toner has a narrow particle size distribution and high fluidity even with a small particle size, so that the transfer efficiency is high and a high-quality image can be obtained. Therefore, it is considered that high-performance printers using polymerized toner will become the mainstream in the future.

However, in various printers and the like using polymerized toner, problems are starting to occur even when a paper feed roller made of a rubber composition containing glass fiber is used.
The reason for this is that the polymer toner is a low-molecular-weight resin produced by emulsion polymerization and chemically fused with pigment, paraffin wax, etc. The resin and wax with such low molecular weight adhere to the rubber roll. It is recognized that it is easy to do. That is, in order to suppress the adhesion of the polymerized toner or wax to the roll surface, it is recognized that it is not sufficient to add glass fiber to the rubber composition.
JP 2002-145466 A

  The present invention has been made in view of the above problems, and even when a polymerized toner is used as the toner, adhesion of the polymerized toner or wax to the roller surface is suppressed, and the surface friction coefficient can be maintained well. It is an object to provide a paper feed roller.

In order to solve the above-mentioned problems, the present invention is based on 100 parts by weight of rubber made of silicone rubber or ethylene-propylene-diene rubber, and 0.1 parts by weight or more of short fibers made of glass fiber or carbon fiber per 100 parts by weight of the rubber. A paper feed roller made of a rubber composition blended in an amount of less than or equal to parts by weight ,
The short fibers have an average fiber diameter of 10 μm or more and 100 μm or less, an average fiber length of 0.01 mm or more and 4 mm or less, and at least a part of the short fibers is 10 degrees or more and 90 degrees or less with a plane in contact with the roller surface . Oriented radially at an angle to expose one end of the short fiber from the roller surface to the roller surface,
The number of the short fibers exposed on the roller surface is 5 or more and 100 or less per 1 mm ^{2 of the} roller surface,
A paper feed roller, wherein the roller is mounted on a copying machine, and the friction coefficient retention rate after passing through 1000 sheets of plain paper on which polymerization toner is printed is 68 to 85% with respect to the initial friction coefficient. providing.

  The paper feed roller of the present invention does not generate a required coefficient of friction on the rubber surface, but exposes short fibers on the roller surface at the angle described above, and feeds paper by friction due to the scratching effect of the short fibers and It is configured to stop the paper. With this configuration, even if heavy toner or wax adheres to the roller surface, the friction coefficient of the roller surface is not reduced compared to the conventional paper feed roller, and various problems caused by the reduction of the friction coefficient are prevented. Can be resolved.

As described above, silicone rubber or ethylene - propylene - the rubber per 100 parts by weight consisting of diene rubber short fibers that are blended at a ratio of less than 2 0 parts by weight or more 0.1 part by weight.
Further, the number of short fibers the end is exposed on the surface of the roller, prior Symbol rubber roll ² per 1mm of the surface, and a 100 inclusive five.
Moreover, it is preferable that the protrusion amount from the roller surface of the said short fiber exposed on the said roller surface shall be 5 micrometers-150 micrometers.
As the short fibers, Ru Tei with carbon fibers or glass fibers.

  In the paper feed roller of the present invention, the short fiber is exposed at the required angle on the surface of the rubber roll, so that polymerized toner, wax, etc. are difficult to adhere, so that the friction coefficient of the roller surface can be maintained well for a long time. it can. Further, even if polymerized toner, wax, paper powder or the like adheres, the coefficient of friction on the roller surface is relatively difficult to decrease. Therefore, by using the paper feed roller of the present invention, good paper passing performance is maintained for a long time in an image forming apparatus using polymerized toner or the like.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a paper feed roller 1 of the present invention. A cylindrical core metal (shaft) 2 is inserted into the hollow cylindrical paper feed roller 1. The thickness of the paper feed roller 1 is not particularly limited, but is, for example, 1 mm to 20 mm, and the length is not particularly limited, but is, for example, 3 mm to 200 mm.

The cross-sectional schematic diagram of FIG. 2 shows an example of a paper feed mechanism using the paper feed roller 1 of FIG. The paper feed mechanism includes a paper feed roller 1, a separation pad 4 and a tray 5. The separation pad 4 and the tray 5 are set at regular intervals, and the upper surface of the separation pad 4 and the upper surface of the tray 5 form an elevation angle. The separation pad 4 is fixed to the substrate 6, and the separation pad 4 and the paper feed roller 1 face each other.
As the paper feed roller 1 rotates in the direction indicated by the arrow R in the figure, the paper 7 on the tray 5 that is in contact with the roller surface is sent out one by one.

  The paper feed roller 1 can be obtained by molding a rubber composition into a predetermined shape and vulcanizing it. The rubber composition contains rubber and short fibers and various additives. Examples of the additive include a crosslinking agent, a filler, a softening agent, a reinforcing agent, a crosslinking aid, a coloring agent, and a deterioration preventing agent. The short fibers are desirably dispersed as uniformly as possible in the rubber composition. When the dispersibility of the short fibers is low, it may be difficult to uniformly distribute the short fibers on the surface of the rubber roll.

Type of rubber, et styrene - propylene - diene rubber, used in the silicone rubber. In the present invention, any type of rubber can be used, that is, a non-oil-extended type comprising only a rubber component and an oil-extended type rubber including an extended oil together with the rubber component.

  From the viewpoint of enhancing the weather resistance and oxidation resistance of the rubber roll, it is preferable to use ethylene-propylene-diene rubber. This is because the main chain of the ethylene-propylene-diene rubber is composed of saturated hydrocarbons and does not contain a double bond, so that deterioration hardly occurs. Therefore, a rubber roll using ethylene-propylene-diene rubber is not easily deteriorated even when exposed to an environment such as a high-concentration ozone atmosphere and light irradiation for a long time.

  From the viewpoint of efficiently suppressing paper slip, it is preferable to use silicone rubber. Since silicone rubber has a property of absorbing oil, even if oil adheres to the surface of the rubber roll, it is difficult to cause paper slip. In particular, in a color copying machine or the like, oil may ooze out from a fixing roller made of silicone rubber. Accordingly, silicone rubber is suitable for a paper feed roller used in a color copying machine or the like.

  Even when ethylene-propylene-diene rubber and other rubber are used in combination, from the viewpoint of obtaining the effect of improving the weather resistance and oxidation resistance of the rubber roll, ethylene-propylene-diene rubber is 50% by weight or more of the total rubber component, Is preferably 80% by weight or more. Even when silicone rubber and other rubber are used in combination, from the viewpoint of obtaining the effect of efficiently suppressing paper slip, the silicone rubber should be 50% by weight or more, further 80% by weight or more of the entire rubber component. Is preferred.

Types of short fibers to be contained in the rubber composition is used mosquitoes over carbon fiber or glass Fiber. These may be used alone or in combination of two or more.

  From the viewpoint of conductivity, it is preferable to use a carbon fiber. For example, short fibers obtained by heat-treating polyacrylonitrile, short fibers obtained by heat-treating fibers produced by spinning petroleum pitch, carbon nanotubes, and the like can be used.

  Conversely, it is preferable to use a glass fiber from the viewpoint that conductivity is not desired. For example, it is possible to use short fibers or the like obtained by drawing molten glass into a fiber shape at a high temperature and cutting it. Examples of the form of the glass fiber include monofilament, chopped strand obtained by cutting glass roving made of a plurality of aligned original yarns (strands), and the like. As the raw material of the glass fiber, for example, an aluminoborosilicate non-alkali glass, soda-lime glass or the like can be used. More specifically, E glass, acid resistant C glass, highly elastic S glass, heat resistant R glass, and the like can be used.

In the present invention, short fibers having an average fiber diameter of 10 μm to 100 μm and an average fiber length of 0.01 mm to 4 mm are used.
When the average fiber diameter of the short fibers is less than 10 μm, the short fibers have insufficient rigidity, and the deterioration of the short fibers exposed on the roller surface is accelerated. On the other hand, if the average fiber diameter of the short fibers exceeds 100 μm, the image on the paper surface in contact with the roller surface may be scratched by the exposed portions of the short fibers.
More preferably, the average fiber diameter of the short fibers is 10 μm or more and 50 μm or less.

In addition, when the average fiber length of the short fibers is less than 0.01 mm, it may be difficult to maintain a good friction coefficient on the rubber roll surface for a long period of time.
On the other hand, if the average fiber length of the short fibers exceeds 4 mm, a good dispersion state of the short fibers cannot be obtained in the rubber composition.
More preferably, the average fiber length of the short fibers is 1 mm or more and 3 mm or less .

The rubber composition has a short fiber content of 0.1% per 100 parts by weight of rubber . 20 parts by weight or more and 1 part by weight that contained in the following proportions.
If the amount of short fibers is less than the above, the effect of suppressing the adhesion of polymerized toner, wax, etc. to the surface of the rubber roll may not be sufficiently obtained. On the other hand, if the amount of short fibers is larger than the above, the rubber roll becomes too hard and a suitable friction coefficient may not be realized .

  As a crosslinking agent that can be included in the rubber composition, an organic peroxide crosslinking agent, an inorganic peroxide crosslinking agent, sulfur, a metal oxide, or the like can be used. The type of the crosslinking agent is preferably selected according to the type of rubber. For example, when using ethylene-propylene-diene rubber or silicone rubber, an organic peroxide crosslinking agent is suitable.

  Examples of the organic peroxide crosslinking agent include dicumyl peroxide (DCP), 1,3-bis (t-butylperoxyisopropyl) benzene, 1,4-bis (t-butylperoxyisopropyl) 3, 3, 5-trimethylcyclohexane, 2,5-dimethyl-2,5-di-t (butylperoxy) hexyne, n-butyl-4,4-bis (t-butylperoxy) valerate, 2,5-dimethyl-2 , 5-bis (t-butylperoxy) hexane and the like. These may be used alone or in combination of two or more.

  When cross-linking ethylene-propylene-diene rubber, dicumyl peroxide is particularly preferable because of high cross-linking efficiency. In the case of crosslinking the silicone rubber, for example, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane is preferable.

  Examples of the filler that can be included in the rubber composition include inorganic fillers such as calcium carbonate, titanium oxide, and magnesium carbonate, ceramic powder, and wood powder. By adding a filler, the mechanical strength of the rubber roll can be improved. The blending amount of the filler is preferably 100 parts by weight or less per 100 parts by weight of rubber.

  As the softening agent that can be included in the rubber composition, oil, plasticizer and the like are used. It is possible to adjust the hardness of the rubber roll by adding a softening agent. As the oil, for example, paraffinic, naphthenic and aromatic mineral oils, synthetic oils composed of hydrocarbon oligomers, process oils and the like can be used. Here, as the synthetic oil, for example, α-olefin oligomer, butene oligomer, amorphous oligomer of ethylene and α-olefin, and the like are preferable. As the plasticizer, for example, dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl separate (DOS), dioctyl adipate (DOA) and the like can be used.

  Carbon black or the like is used as a reinforcing agent that can be included in the rubber composition. By adding carbon black, it is possible to improve the wear resistance of the rubber roll. As the carbon black, for example, carbon black such as HAF, MAF, FEF, GPF, SRF, SAF, MT, and FT can be used. From the viewpoint of dispersibility in the rubber composition, the particle size of carbon black is preferably 10 μm or more and 100 μm or less.

  The rubber composition may be prepared by a conventional method that has been conventionally performed. For example, a rubber composition can be obtained by kneading a compound composed of rubber, short fibers, a crosslinking agent and the like using a known rubber kneading apparatus such as an open roll, a Banbury mixer, a kneader or the like. The temperature of the compound during kneading is, for example, 70 ° C. to 100 ° C., and the kneading time is, for example, 3 minutes to 10 minutes.

  As a method for vulcanizing / molding the rubber composition, any method may be adopted as long as the orientation of the short fibers can be controlled. However, when the rubber composition is molded by extrusion molding, the short fibers are oriented in a direction parallel to the extrusion direction. In this case, the short fibers are oriented in a direction substantially parallel to the surface of the molded product. Therefore, it is desirable to vulcanize and mold the rubber composition by a method other than extrusion molding. A preferred molding method is transfer molding.

  For example, an unvulcanized rubber composition is introduced into a predetermined transfer molding die and heated at a temperature of, for example, 150 ° C. to 200 ° C. for about 5 minutes to 30 minutes, thereby adding the rubber composition. Sulfur and tube forming can be performed simultaneously. When molding a rubber tube by transfer molding, it is necessary to control the orientation of the contained short fibers so as to be oriented in the radial direction. Such control can be easily performed by adjusting the mold shape, the pressure for introducing the rubber composition into the mold, and the like.

  Thereafter, the molded rubber tube is polished with a cylindrical grinder until it has a desired outer diameter, and cut into a desired length, whereby a rubber roll can be obtained. The short fibers contained in the obtained rubber roll are oriented in a direction that forms a predetermined angle with an arbitrary plane in contact with the rubber roll surface. Here, if the angle is less than 10 degrees, the effect of suppressing the adhesion of polymerized toner, wax and the like to the surface of the rubber roll cannot be sufficiently obtained. Therefore, it becomes difficult to maintain the friction coefficient of the rubber roll surface well for a long period of time. Therefore, the angle is preferably 10 degrees or more, more preferably 20 degrees or more, and ideally 90 degrees.

  In addition, when the angle is 10 degrees or more, even if polymerized toner, wax or the like adheres to the surface of the rubber roll, the friction coefficient on the surface of the rubber roll is relatively reduced due to the effect of scratching the paper surface by short fibers. Hard to do.

One end of the short fiber is exposed on the surface of the rubber roll obtained by surface polishing. The number of short fibers having one exposed end is 5 or more and 100 or less per 1 mm ^{2 of} the rubber roll surface . If the number of short fibers exposed per 1 mm ^{2 of the} rubber roll surface is too small, the effect of suppressing the adhesion of polymerized toner, wax, etc. to the rubber roll surface is sufficient even if the short fibers are properly oriented. May not be obtained.

Examples of the present invention and comparative examples will be described in detail below.
[Example 1]
100 parts by weight of ethylene-propylene-diene (EPDM) rubber, 5 parts by weight of silicon oxide, 10 parts by weight of calcium carbonate, 10 parts by weight of titanium oxide, 1 part by weight of carbon black, 0.5 part by weight of stearic acid, peroxide crosslinking agent (1) 3 parts by weight and 2 parts by weight of glass fibers as short fibers were put into a closed kneader and kneaded to obtain a rubber composition.

Here, the following was used as each component described above.
EPDM: “Esplen 505A (trade name)” manufactured by Sumitomo Chemical Co., Ltd.
Silicon oxide: “Nipsil VN3 (trade name)” manufactured by Nippon Silica Kogyo Co., Ltd.
Calcium carbonate: “BF300 (trade name)” manufactured by Bihoku Flour Industry Co., Ltd.
Titanium oxide: “Kronos titanium oxide KR380 (trade name)” manufactured by Titanium Industry Co., Ltd.
Carbon black: “Seast SO (trade name)” manufactured by Tokai Carbon Co., Ltd.
Stearic acid: “Tsubaki (trade name)” manufactured by Nippon Oil & Fats Co., Ltd.
Peroxide crosslinking agent (1): “DCP (Dicumyl peroxide) (trade name)” manufactured by NOF Corporation
Glass fiber 1: “chopped strand BM33 (trade name)” manufactured by NSG Vetrotex Co., Ltd. Average fiber diameter 33 μm, average fiber length 3 mm
Glass fiber 2: The average fiber diameter of “chopped strand BM38 (trade name)” manufactured by NSG Vetrotex Co., Ltd. is 11 μm, and the average fiber length is 3 mm.

Next, the obtained rubber composition was introduced into a predetermined transfer mold, heated at 160 ° C. for 20 minutes, and simultaneously molded and vulcanized. As a result, the inner diameter was 9 mm, the outer diameter was 20 mm, and the length was 50 mm. A rubber tube was obtained. The rubber tube was polished with a cylindrical grinder until the outer diameter was 15 mm and cut to a length of 24 mm. A rubber core obtained by cutting was filled with a special metal core to complete a paper feed roller.

[Examples 2 to 11 and Comparative Examples 1 to 3]
Paper feed rollers of Examples 2 to 11 and Comparative Examples 1 to 3 were produced in the same manner as in Example 1 except that the composition of the rubber composition was changed as shown in Table 1.
In Table 1, the unit of the numerical value indicating the component amount is parts by weight.

As each component in Table 1, the same product name as in Example 1 was used for the same component as in Example 1, and the following was used for the other components.
Silicone rubber: “TSE221-5U (trade name)” manufactured by GE Toshiba Silicone Co., Ltd.
Peroxide crosslinking agent (2): “TC8 (trade name)” manufactured by GE Toshiba Silicone Co., Ltd.
Carbon fiber: “Kureha Chop C106T (trade name)” manufactured by Kureha Chemical Industry Co., Ltd.
The carbon fiber “Kureha Chop C106T” had an average fiber diameter of 9 μm and an average fiber length of 3 mm.

[Evaluation]
The following measurements and evaluations were performed on the paper feed rollers of each Example and each Comparative Example produced as described above. The results are shown in Table 1.

(Short fiber orientation)
An enlarged photograph of the surface and cross section of the rubber roll was taken to confirm the orientation of the short fibers. As an example, FIG. 3 shows a photograph of the magnification of 100 times taken on the rubber roll surface of Example 1, and FIG. 4 shows a photograph of the magnification of 300 times. FIG. 5 shows a photograph of the magnification of 100 times taken on the surface of the rubber roll of Comparative Example 3. Furthermore, from the enlarged photograph of the rubber roll cross section, the angle formed between the short fibers and the plane in contact with the rubber roll surface was determined.

(Paper delivery status)
A paper feeding roller was attached to “VIVECE 455 (trade name)” manufactured by Fuji Xerox Co., Ltd., and 1000 sheets of plain paper on which printing with polymerized toner was performed were passed, and the state of paper passing was observed. Here, PB paper (trade name) manufactured by Canon Inc. was used as the plain paper 9.
The paper passing status was judged in two stages: ○: good, x: non-feed and double feed.

(Coefficient of friction)
The coefficient of friction was measured by the method schematically shown in FIG. First, the other end of the plain paper 9 of 60 mm × 210 mm size having one end connected to the load cell 10 was sandwiched between the paper feed roller 3 and the fixed plate 8 made of polytetrafluoroethylene (PTFE). Next, a load W of 250 gf was applied from the paper feed roller toward the plate 8.

  Next, the paper feed roller 3 was rotated at a peripheral speed of 300 mm / second in the direction indicated by the arrow R in FIG. 6 under conditions of a temperature of 23 ° C. and a humidity of 55%. And the conveyance force F applied to the load cell 10 at this time was measured. The friction coefficient μ was determined from the measured conveying force F (gf) and load W (W = 250 gf) using the following formula 1.

(Formula 1)
μ = F (gf) / W (gf)

  Here, the initial friction coefficient μ0 and the friction coefficient μ1000 at the end of the observation of the sheet passing state were obtained. Table 1 shows the initial friction coefficient μ0 and the friction coefficient retention ratio X at the end of the paper feeding state observation. The coefficient of friction retention X was determined using the following formula 2.

(Formula 2)
X (%) = (μ1000 / μ0) × 100

[Consideration of results]
As shown in Table 1, when the short fibers formed a certain angle with the plane in contact with the roll surface, the initial friction coefficient was high and the paper passing condition was also good. Moreover, the friction coefficient retention rate exceeded 70% in any of the examples. As the amount of short fibers increased, the initial friction coefficient tended to decrease slightly, but the level of friction coefficient required for the paper feed roller was maintained at a sufficient level. The coefficient of friction retention tended to improve conversely as the amount of short fibers increased.

The initial friction coefficient was slightly lower when silicone rubber was used than when EPDM rubber was used, but the friction coefficient retention was better when silicone rubber was used. In Comparative Examples 1 and 2 in which no short fiber was used, a high friction coefficient was obtained in the initial stage. However, the coefficient of friction retention was greatly reduced as compared to each example.
Even in Comparative Example 3 in which the short fibers were oriented parallel to the roller surface, only a very low coefficient of friction retention was obtained despite the use of the short fibers. Moreover, even if it compared with the comparative example 2 which does not use a short fiber, the friction coefficient retention was hardly improved. Such a result is that, in order to suppress the adhesion of polymerized toner, wax, etc. to the surface of the wax, and to maintain a good friction coefficient on the roller surface for a long period of time, the short fiber is in contact with the flat surface in contact with the roller surface. This shows that it is extremely effective to form a certain angle.

  The present invention improves the reliability of a paper feed roller used for paper feed in various printers, electrostatic copying machines, plain paper facsimile machines, automatic deposit payment machines (ATMs), and the like. This is extremely useful in a paper feeding mechanism such as a high performance printer.

It is a perspective view of the paper feed roller 1 of the present invention. It is a cross-sectional schematic diagram which shows an example of the paper feed mechanism using the paper feed roller of FIG. FIG. 3 is a photograph at a magnification of 100 times showing a surface of a rubber roll of Example 1. FIG. 2 is a photograph at a magnification of 300 times obtained by photographing the rubber roll surface of Example 1. FIG. 6 is a photograph of a magnification of 100 times taken on the surface of a rubber roll of Comparative Example 3. It is a figure which shows typically the method of measuring the friction coefficient of a paper feed roller.

Explanation of symbols

1 Paper feed roller 2 Core metal (shaft)
4 Separation pad 5 Tray 6 Substrate 7 Paper 8 PTFE board 9 Plain paper 10 Load cell

Claims (3)

From 100 parts by weight of rubber made of silicone rubber or ethylene-propylene-diene rubber, from a rubber composition in which short fibers made of glass fiber or carbon fiber are blended in an amount of 0.1 to 20 parts by weight per 100 parts by weight of the rubber. A paper feed roller,
The short fibers have an average fiber diameter of 10 μm or more and 100 μm or less, an average fiber length of 0.01 mm or more and 4 mm or less, and at least a part of the short fibers is 10 degrees or more and 90 degrees or less with a plane in contact with the roller surface . Oriented radially at an angle to expose one end of the short fiber from the roller surface to the roller surface,
The number of the short fibers exposed on the roller surface is 5 or more and 100 or less per 1 mm ^{2 of the} roller surface,
A paper feed roller having a friction coefficient holding ratio of 68 to 85% with respect to an initial friction coefficient after passing 1000 sheets of plain paper on which the roller is mounted on a copying machine and printing is performed with polymerized toner. The paper feed roller according to claim 1, wherein a protruding amount of the short fibers from the roller surface is 5 μm to 150 μm.   An image forming apparatus comprising the paper feed roller according to claim 1.